Corrosion inhibitor system for functional fluids

ABSTRACT

The SAE corrosion specifications and other SAE specifications for functional fluids are met by the use of an effective amount of an inhibitor system consisting essentially of: 0-81.4% N-DODECYLDIMETHYLAMINE 0-81.4% T-BUTYLAMINE 16.6-98% Phosphite ester of an alkyla ted phenol 1.8-83% Polymerized trimethyl dihydr oquinoline 0.2-9.4% Benzotriazole BY WEIGHT.

Q Umted States Patent 1151 Avery et al. [451 Feb. 8, 1972 CORROSIONINHIBITOR SYSTEM FOR 3,338,835 8/1967 Wright ..252/77 x FUNCTIONALFLUIDS 3,341,456 9 1967 Sawyer ..252/75 x 3,346,501 10/1967 Boehmer..252/75 X [72] Inventors: Lowell R. Avery; Wayne A. Conklin, both ofMidland, Mich. OTHER PUBLICATIONS [73] Assignee: h Dow Chemical CompanyMidland; Propylene carbonate," Technical Bulletin. pp. l-3.

Mich Jefferson Chen ig lgo. (1960) [22] Flled: 1969 Primary Examiner-Leon D. Rosdol [21] Appl. No.: 793,177 Assistant Examiner-Har1'is A.Pitlick Attorney-Griswold & Burdick and C. E. Rehberg [52] U.S. Cl..252/78, 252/77, 252/389,

252,390 57 ABSTRACT 51 11 1.01 ..C09k3/00,C23f11/16 The SAE corrosionSpecifications and other SAE Specifica [58] Fleld of Search ..252/7075,77, M tions for functional fluids are met by the use of an effective252/78 393; 260/3402 amount of an inhibitor system consistingessentially of:

0-81.4% n-dodecyldimethylamine [56] 7 References C1led 0 81.4% tbutylamine UNITED STATES PATENTS l6.698% Phosphile ester of an alkylatedphenol 3,342,736 9/1967 Nankee ..252/7s gjig gg gf ffs d'hydmqumolme2,799,659 7/1957 ..252/7'7 x ,332,980 7/1967 ..252/77 x by welght-3,334,054 8/1967 Howard et al ..252/75 X 6 Claims, N0 Drawings CORROSIONINHIBITOR SYSTEM FOR FUNCTIONAL FLUIDS BACKGROUND OF THE INVENTION Thedevelopment of low hygroscopic functional fluids has been severelyimpaired by the absence of a compatible corrosion inhibitor system thatwill meet the SAE specifications.

SUMMARY OF THE INVENTION According to the present invention, the SAEcorrosion specifications as well as other SAE specifications are met inlow hygroscopic and higher hygroscopic functional fluids by the additionof a effective amount of a corrosion inhibitor con sisting essentiallyof:

and

02-94% Benzotriazole.

As a preferred embodiment of the present invention, the corrosioninhibitor may contain by weight:

17-5 6% ndodecyldimethylamine l756% t-Butylamine l 148% PEAP Z-l 6% TMDHQ 0.5-2.31: Benzotriazole.

The corrosion inhibitor of the invention may be added to a functionalfluid in any effective amount. The amount required for adequateprotection varies as the inhibitor is used in different fluid systems;however, as a general rule amounts of about 0.25 to percent by weight ofthe functional fluid are acceptable with amounts of 0.5 to 1 percentusually being suf ficient to meet the corrosion standards of the SAE.

The functional fluid of the present invention may be any of thefunctional fluids that are generally used, particularly those basedpredominantly on polyoxyalkylene glycols, polyoxyalkylene glycol esters,polyoxyalkylene glycol ethers, alkylene carbonates and the like.

The low hydroscopic functional fluids are of special interest in theinvention. These fluids are distinguished from other functional fluidsby the absence or low concentration of free hydroxyl groups. Thus, theglycol ethers, glycol esters and alkylene carbonates form the basis formost such fluids.

In a preferred embodiment of the present invention, the basic functionalfluid is an alkylene or poiyoxyalkylene glycol ether or ester and acyclic alkylene carbonate. The ether may suitably contain one to sixoxyalkylene units of two to four carbon atoms each capped with one ortwo alkyl ether groups of one to six carbon atoms each. Thus, suitableglycol ethers include the mono and di methyl, ethyl, propyl, butyl andhexyl ethers of the mono and polyoxyethylene, -propylene and -butyleneglycols containing up to about six oxyalkylene groups.

By reacting the alkylene or polyoxyalkylene glycol with a carboxylicacid, the glycol esters may be formed. One or two carboxylic acid groupsof up to six carbon atoms each may suitably be used to form the glycolester. The polyoxyalkylene glycol may contain up to about sixoxyalkylene groups of two to four carbon atoms each. Thus, the glycolesters suitable for the functional fluid may suitably include the monothrough hexaoxyethylene, -propylene and -butylene mono and di acetates,propionates, butyrates, and hexanoates and the like.

The glycol ether or ester in the preferred functional fluid of theinvention may suitably comprise 50 to about l00% of the fluid with 60 to95% being preferred.

The second component of the preferred low hygroscopic functional fluidis the cyclic alkylene carbonate. These may suitably be the cyclicethylene, propylene or butylene carbonates. While the vicinal alkylenecarbonates are preferred, the 1,3- and 1,4-alkylene carbonates are alsouseful. The cyclic carbonate may comprise 0.l to 30% of the fluid with 3to 20% being preferred.

In the preferred functional fluid of the invention. les than about 25%by weight may suitably be a polyglycol. Although the presence of apoiyglycol diminishes the low hygroscopic properties of the fluid due toits free hydroxyls. the polyglycol may be added to obtain other desiredproperties. These poiyglycols are polyoxyethylene, polyoxypropylene andpolyoxybutylenc glycols having a molecular weight of 4004.000.

SPECIFIC EMBODIMENTS Example 1 A functional fluid consisting of 72% byweight of tetraoxyethylene glycol dipropionate, 18% of cyclic vicinalpropylene carbonate and 10% of a polyoxypropylene glycol having anaverage molecular weight of 2,000 was examined under SAE tests 7ORI and7OR3. After this standard was run, 0.76% by weight of the followingcomposition was added:

33% n-dodecyldimethylamine 33% t-butylamine 26.4% PEAP 6.6% TMDHQ L070Benzotriazole.

The same tests were run, and the results of these tests are compared inTable I.

TABLE I Results Require- Without With merits R1 Inhibi- Inhibitor Testand 70R3 tors system Corrosion, (weight loss in mg./sq.

Tinned iron. Max. 0.2..." 0.. 0.01. e1 MaX.0.2 0.28- 0.00. Aluminum Max.0. .06 0.00. Cast iron Max. 0.2.... .30 +0.19

(gain). Brass Max. 0.4. .07 0.01. Oopper Max. 0.4 .11 0.10. Ptttmg orroughening of strips Max. None Ye? 1 None s ee Al, Fe. J elling offluid/water mixture do Do. Crystalline deposit on glass jar -do D0.

walls or metal strips. Sedimentation, percent by volume- Max. 0.10% D0.pH of water/fluid mixture 711.5 5.6 9.3. Disintegration of rubber cup asevi- Max. None None.

denced by excessive tackiness or blisters. Sloughing of rubber cup asevido D0.

denced by carbon black separaon. Decrease in hardness of rubber cup.Max. 15 9. Increase in base diameter of rubber Max. 0.055 0.020 in.

cup. in.

The corrosion inhibitor compositions of the invention are also effectivein other functional fluid compositions such as those disclosed in US.Pat. Nos. 3,324,035", 3,062,747; 3,342,736 and 3,206,486.

We claim:

I. A low hygroscopic functional fluid consisting essentially of 50-l00%by weight of a compound selected from the group consisting ofpolyoxyalkylene glycol esters having one to six oxyalkylene units of twoto four carbon atoms each capped with one or two carboxylic acid groupsof up to six carbons each and polyoxyalkylene glycol ethers having oneto six oxyalkylene units of two to four carbon atoms each capped withone or two alkyl groups of one to six carbons each, and mixturesthereof; a cyclic alkylene carbonate where the alkylene is selected fromthe group consisting of ethylene, propylene and butylene; less thanabout 25 percent by weight of a polyoxyalkylene glycol having amolecular weight of 4004,000 where the polyoxyalkylene is selected fromthe group consisting of polyoxyethylene, polyoxypropylene andpolyoxybutylene; and an effective amount to inhibit corrosion of acorrosion inhibitor composition consisting essentially of:

-81 .4% n-Dodecyldimethylamine 0-8l .4% t-Butylamine l6.698% Tri(tertiary-amylphenyl) phosphite containing up to weight percentdicyclohexyl amine. l.883% Polymerized trimethyl dihydroquinoline0.29.4% Benzotriazole all parts being by weight.

2. The functional fluid of claim I wherein the corrosion inhibitorcomposition consists essentially of:

l7-56% n-dodecyldimethylumine 17-56% thutylamine l l-4likTri(tcrtiury-nmylphenyl) phosphit:

containing up to It) weight percent dicyclohelylnmin:

2-l 6% Polymerized trirrtethyl dihydroquinoline 0.5-2.3% Benzotriazole.

2. The functional fluid of claim 1 wherein the corrosion inhibitorcomposition consists essentially of: 17-56% n-dodecyldimethylamine17-56% t-butylamine 11-48% Tri(tertiary-amylphenyl) phosphite containingup to 10 weight percent dicyclohexylamine 2-16% Polymerized trimethyldihydroquinoline 0.5-2.3% Benzotriazole.
 3. The functional fluid ofclaim 1 wherein the corrosion inhibitor constitutes 0.25 to 5% by weightof the fluid.
 4. The functional fluid of claim 1 wherein the corrosioninhibitor constitutes 0.5 to 1% by weight of the fluid.
 5. Thefunctional fluid of claim 1 wherein the cyclic alkylene carbonateconstitutes 0.1 to 30%.
 6. The functional fluid defined in claim 1wherein 60 to 95% by weight of the fluid is the ether or ester and 3 to20% by weight is the cyclic alkylene carbonate.